README.md

525. Contiguous Array

Given a binary array nums, return the maximum length of a contiguous subarray with an equal number of 0 and 1.

Example 1:

Input: nums = [0,1]
Output: 2
Explanation: [0, 1] is the longest contiguous subarray with an equal number of 0 and 1.

Example 2:

Input: nums = [0,1,0]
Output: 2
Explanation: [0, 1] (or [1, 0]) is a longest contiguous subarray with equal number of 0 and 1.

Constraints:

• 1 <= nums.length <= 105
• nums[i] is either 0 or 1.

Solutions (Ruby)

1. HashMap

# @param {Integer[]} nums
# @return {Integer}
def find_max_length(nums)
  count = 0
  counts = { 0 => -1 }
  ret = 0

  (0...nums.size).each do |i|
    count += nums[i] == 0 ? 1 : -1
    counts[count] = i unless counts.include?(count)
    ret = [ret, i - counts[count]].max
  end

  ret
end

Solutions (Rust)

1. HashMap

use std::collections::HashMap;

impl Solution {
    pub fn find_max_length(nums: Vec<i32>) -> i32 {
        let mut count = 0;
        let mut counts = vec![(0, -1)].into_iter().collect::<HashMap<_, _>>();
        let mut ret = 0;

        for i in 0..nums.len() as i32 {
            match nums[i as usize] {
                0 => count += 1,
                _ => count -= 1,
            }
            if !counts.contains_key(&count) {
                counts.insert(count, i);
            }
            ret = ret.max(i - counts.get(&count).unwrap());
        }

        ret
    }
}